The specific purpose of this research project is to characterize the receptor for interleukin-2 (IL-2)\on surface membranes of normal and malignant human lymphocytes. We plan to use two probes for these studies: (1)\purified IL-2 and (2)\monoclonal antibodies (MoAbs) reacting with the receptor for IL-2. Near-complete purification of IL-2 can be achieved by one-step affinity chromatography on Amicon Blue A gel, a recently devised method. A new series of affinity matrices has also been identified and will be applied to the complete purification of IL-2. Binding studies with radiolabeled IL-2 molecules will allow the identification and characterization of IL-2 receptor on activated normal T-lymphocyte subpopulations, as well as cells from patients with lymphoproliferative malignancies. We will examine the kinetics of "down regulation" and degradation of IL-2-receptor complex and re-expression of the IL-2 receptor. MoAbs to IL-2 receptor will allow further characterization of the receptor and will provide a source of IL-2 receptor ligands in milligram quantities. These MoAbs will be used to screen normal and malignant T-lymphocyte subpopulations for both quantitative differences in IL-2 receptor content as well as qualitative differences (KD; effects upon metabolism). Functional studies of the Il-2 receptor will be carried out with agonistic MoAbs that stimulate the receptor, imitating IL-2 activity, and with antagonistic MoAbs that block the receptor, inhibiting lymphoproliferation. The MoAbs will also allow initial affinity purification of the receptor. This project has importance for understanding the biological role of IL-2 receptors in the control of normal and malignant lymphoproliferation and for identifying quantitative and qualitative differences in IL-2 receptors on normal and malignant human lymphocytes.